interface/glcanvas.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        glcanvas.h
   3 // Purpose:     interface of wxGLContext
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10     @class wxGLContext
  11     @wxheader{glcanvas.h}
  12
  13     An instance of a wxGLContext represents the state of an OpenGL state machine
  14     and the connection between OpenGL and the system.
  15
  16     The OpenGL state includes everything that can be set with the OpenGL API:
  17     colors, rendering variables, display lists, texture objects, etc.
  18     Although it is possible to have multiple rendering contexts share display lists
  19     in order to save resources,
  20     this method is hardly used today any more, because display lists are only a
  21     tiny fraction of the overall state.
  22
  23     Therefore, one rendering context is usually used with or bound to multiple
  24     output windows in turn,
  25     so that the application has access to the complete and identical state while
  26     rendering into each window.
  27
  28     Binding (making current) a rendering context with another instance of a
  29     wxGLCanvas however works only
  30     if the other wxGLCanvas was created with the same attributes as the wxGLCanvas
  31     from which the wxGLContext
  32     was initialized. (This applies to sharing display lists among contexts
  33     analogously.)
  34
  35     Note that some wxGLContext features are extremely platform-specific - its best
  36     to check your native platform's glcanvas header (on windows include/wx/msw/glcanvas.h) to see what features your native platform provides.
  37
  38     @library{wxgl}
  39     @category{gl}
  40
  41     @see wxGLCanvas
  42 */
  43 class wxGLContext : public wxObject
  44 {
  45 public:
  46     /**
  47         Constructor.
  48
  49         @param win
  50             The canvas that is used to initialize this context. This parameter is
  51         needed only temporarily,
  52             and the caller may do anything with it (e.g. destroy the window) after the
  53         constructor returned.
  54             It will be possible to bind (make current) this context to any other
  55         wxGLCanvas that has been created
  56             with equivalent attributes as win.
  57         @param other
  58             Context to share display lists with or @NULL (the default) for no sharing.
  59     */
  60     wxGLContext(wxGLCanvas* win, const wxGLContext* other = NULL);
  61
  62     /**
  63         Makes the OpenGL state that is represented by this rendering context current
  64         with the wxGLCanvas @e win.
  65         Note that @a win can be a different wxGLCanvas window than the one that was
  66         passed to the constructor of this rendering context.
  67         If  @e RC  is an object of type wxGLContext, the statements @e
  68         RC.SetCurrent(win); and @e win.SetCurrent(RC); are equivalent,
  69         see wxGLCanvas::SetCurrent.
  70     */
  71     void SetCurrent(const wxGLCanvas& win);
  72 };
  73
  74 /**
  75     Constants for use with wxGLCanvas.
  76
  77     Notice that not all implementation support options such as stereo,
  78     auxiliary buffers, alpha channel, and accumulator buffer, use
  79     wxGLCanvas::IsDisplaySupported() to check for individual attributes support.
  80  */
  81 enum
  82 {
  83     /// Use true color palette (on if no attributes at all specified).
  84     WX_GL_RGBA = 1,
  85
  86     /// Specifies the number of bits for buffer if not WX_GL_RGBA.
  87     WX_GL_BUFFER_SIZE,
  88
  89     /// Must be followed by 0 for main buffer, >0 for overlay, <0 for underlay.
  90     WX_GL_LEVEL,
  91
  92     /// Use double buffering if present (on if no attributes specified).
  93     WX_GL_DOUBLEBUFFER,
  94
  95     /// Use stereoscopic display.
  96     WX_GL_STEREO,
  97
  98     /// Specifies number of auxiliary buffers.
  99     WX_GL_AUX_BUFFERS,
 100
 101     /// Use red buffer with most bits (> MIN_RED bits)
 102     WX_GL_MIN_RED,
 103
 104     /// Use green buffer with most bits (> MIN_GREEN bits)
 105     WX_GL_MIN_GREEN,
 106
 107     /// Use blue buffer with most bits (> MIN_BLUE bits)
 108     WX_GL_MIN_BLUE,
 109
 110     /// Use alpha buffer with most bits (> MIN_ALPHA bits)
 111     WX_GL_MIN_ALPHA,
 112
 113     /// Specifies number of bits for Z-buffer (typically 0, 16 or 32).
 114     WX_GL_DEPTH_SIZE,
 115
 116     /// Specifies number of bits for stencil buffer.
 117     WX_GL_STENCIL_SIZE,
 118
 119     /// Specifies minimal number of red accumulator bits.
 120     WX_GL_MIN_ACCUM_RED,
 121
 122     /// Specifies minimal number of green accumulator bits.
 123     WX_GL_MIN_ACCUM_GREEN,
 124
 125     /// Specifies minimal number of blue accumulator bits.
 126     WX_GL_MIN_ACCUM_BLUE,
 127
 128     /// Specifies minimal number of alpha accumulator bits.
 129     WX_GL_MIN_ACCUM_ALPHA
 130
 131 };
 132
 133 /**
 134     @class wxGLCanvas
 135     @wxheader{glcanvas.h}
 136
 137     wxGLCanvas is a class for displaying OpenGL graphics. It is always used in
 138     conjunction with wxGLContext as the context can only be
 139     be made current (i.e. active for the OpenGL commands) when it is associated to
 140     a wxGLCanvas.
 141
 142     More precisely, you first need to create a wxGLCanvas window and then create an
 143     instance of a wxGLContext that is initialized with this
 144     wxGLCanvas and then later use either wxGLCanvas::SetCurrent
 145     with the instance of the wxGLContext or
 146     wxGLContext::SetCurrent with the instance of
 147     the wxGLCanvas (which might be not the same as was used
 148     for the creation of the context) to bind the OpenGL state that is represented
 149     by the rendering context to the canvas, and then finally call
 150     wxGLCanvas::SwapBuffers to swap the buffers of
 151     the OpenGL canvas and thus show your current output.
 152
 153     Notice that previous versions of wxWidgets used to implicitly create a
 154     wxGLContext inside wxGLCanvas itself. This is still supported in the current
 155     version but is deprecated now and will be removed in the future, please update
 156     your code to create the rendering contexts explicitly.
 157
 158     To set up the attributes for the canvas (number of bits for the depth buffer,
 159     number of bits for the stencil buffer and so on) you should set up the correct
 160     values of
 161     the @e attribList parameter. The values that should be set up and their
 162     meanings will be described below.
 163
 164     Notice that OpenGL is not enabled by default. To switch it on, you need to edit
 165     setup.h under Windows and set @c wxUSE_GLCANVAS to 1 (you may also need
 166     to have to add @c opengl32.lib and @c glu32.lib to the list of libraries
 167     your program is linked with). On Unix, pass @c --with-opengl to configure.
 168
 169     @library{wxgl}
 170     @category{gl}
 171
 172     @see wxGLContext
 173 */
 174 class wxGLCanvas : public wxWindow
 175 {
 176 public:
 177     /**
 178         Creates a window with the given parameters. Notice that you need to create and
 179         use a wxGLContext to output to this window.
 180         If
 181
 182         @param attribList is not specified, double buffered RGBA mode is used.
 183
 184         parent
 185             Pointer to a parent window.
 186         @param id
 187             Window identifier. If -1, will automatically create an identifier.
 188         @param pos
 189             Window position. wxDefaultPosition is (-1, -1) which indicates that
 190         wxWidgets
 191             should generate a default position for the window.
 192         @param size
 193             Window size. wxDefaultSize is (-1, -1) which indicates that wxWidgets should
 194             generate a default size for the window. If no suitable size can be found,
 195         the window will be sized to 20x20 pixels so that the window is visible but obviously not correctly sized.
 196         @param style
 197             Window style.
 198         @param name
 199             Window name.
 200         @param attribList
 201             Array of integers. With this parameter you can set the device
 202             context attributes associated to this window. This array is
 203             zero-terminated: it should be set up with constants described in
 204             the table above. If a constant should be followed by a value, put
 205             it in the next array position. For example, the WX_GL_DEPTH_SIZE
 206             should be followed by the value that indicates the number of bits
 207             for the depth buffer, e.g:
 208             @code
 209             attribList[n++] = WX_GL_DEPTH_SIZE;
 210             attribList[n++] = 32;
 211             attribList[n] = 0; // terminate the list
 212             @endcode
 213             If the attribute list is not specified at all, i.e. if this
 214             parameter is @NULL, the default attributes including @c WX_GL_RGBA
 215             and @c WX_GL_DOUBLEBUFFER are used. But notice that if you do
 216             specify some attributes you also need to explicitly include these
 217             two default attributes in the list if you need them.
 218         @param palette
 219             Palette for indexed colour (i.e. non WX_GL_RGBA) mode.
 220             Ignored under most platforms.
 221     */
 222     wxGLCanvas(wxWindow* parent, wxWindowID id = wxID_ANY,
 223                const int* attribList = NULL,
 224                const wxPoint& pos = wxDefaultPosition,
 225                const wxSize& size = wxDefaultSize,
 226                long style = 0,
 227                const wxString& name = "GLCanvas",
 228                const wxPalette& palette = wxNullPalette);
 229
 230     /**
 231         Determines if a canvas having the specified attributes is available.
 232         Returns @true if attributes are supported.
 233
 234         @param attribList
 235             See attribList for wxGLCanvas().
 236     */
 237     static bool IsDisplaySupported(const int* attribList = NULL);
 238
 239     /**
 240         Sets the current colour for this window (using @c glcolor3f()), using the
 241         wxWidgets colour database to find a named colour.
 242     */
 243     void SetColour(const wxString& colour);
 244
 245     /**
 246         Makes the OpenGL state that is represented by the OpenGL rendering context
 247         @a context current, i.e. it will be used by all subsequent OpenGL calls.
 248         This is equivalent to wxGLContext::SetCurrent
 249         called with this window as parameter.
 250         Note that this function may only be called when the window is shown on screen,
 251         in particular it can't usually be called from the constructor as the window
 252         isn't yet shown at this moment.
 253         Returns @false if an error occurred.
 254     */
 255     bool SetCurrent(const wxGLContext context);
 256
 257     /**
 258         Swaps the double-buffer of this window, making the back-buffer the front-buffer
 259         and vice versa,
 260         so that the output of the previous OpenGL commands is displayed on the window.
 261         Returns @false if an error occurred.
 262     */
 263     bool SwapBuffers();
 264 };
 265